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Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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MIC-Info: RSA-MD5,RSA,
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<SEC-DOCUMENT>0001140361-09-029628.txt : 20091217
<SEC-HEADER>0001140361-09-029628.hdr.sgml : 20091217
<ACCEPTANCE-DATETIME>20091217194200
ACCESSION NUMBER:		0001140361-09-029628
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20091216
FILED AS OF DATE:		20091217
DATE AS OF CHANGE:		20091217

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			CENTURY ALUMINUM CO
		CENTRAL INDEX KEY:			0000949157
		STANDARD INDUSTRIAL CLASSIFICATION:	PRIMARY PRODUCTION OF ALUMINUM [3334]
		IRS NUMBER:				133070826
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		2511 GARDEN ROAD
		STREET 2:		BUILDING A SUITE 200
		CITY:			MONTEREY
		STATE:			CA
		ZIP:			93940
		BUSINESS PHONE:		3042736000

	MAIL ADDRESS:	
		STREET 1:		2511 GARDEN ROAD
		STREET 2:		BUILDING A SUITE 200
		CITY:			MONTEREY
		STATE:			CA
		ZIP:			93940

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			BLESS MICHAEL A
		CENTRAL INDEX KEY:			0001204903

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-34474
		FILM NUMBER:		091248359

	MAIL ADDRESS:	
		STREET 1:		C/O ROCKWELL INTERNATIONAL INC
		STREET 2:		777 E. WISCONSIN AVE #1400
		CITY:			MILWAUKEE
		STATE:			WI
		ZIP:			53202
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>doc1.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2009-12-16</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000949157</issuerCik>
        <issuerName>CENTURY ALUMINUM CO</issuerName>
        <issuerTradingSymbol>CENX</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001204903</rptOwnerCik>
            <rptOwnerName>BLESS MICHAEL A</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>CENTURY ALUMINUM COMPANY</rptOwnerStreet1>
            <rptOwnerStreet2>2511 GARDEN ROAD, BLDG A, SUITE 200</rptOwnerStreet2>
            <rptOwnerCity>MONTEREY</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>93940</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Exec. VP and CFO</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2009-12-16</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>15462</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>14.39</value>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>83718</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">Represents the average sale price of 15,462 shares in two separate transactions:  15,162 shares at $14.39 and 300 shares at $14.40.</footnote>
        <footnote id="F2">Includes unvested shares of performance share units granted to the Reporting Person in connection with the Issuer's 2008-2010 and 2009-2011 Performance Share Program Periods under a Rule 16b-3(d) plan, all of which vest on December 31, 2010 and January 1, 2011 respectively, or earlier, upon the Reporting Person's termination of employment with the Issuer and its subsidiaries due to death, disability, termination other than for cause or other reason approved by the Compensation Committee of the Issuer's Board of Directors.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>William J. Leatherberry, Attorney-in-Fact for Michael A. Bless</signatureName>
        <signatureDate>2009-12-17</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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